1. Field of the Invention
Implementations of various techniques described herein generally relate to techniques for performing oilfield operations on subterranean formations having reservoirs therein, and more particularly, to techniques for simulating oilfield operations.
2. Description of the Related Art
The following descriptions and examples do not constitute an admission as prior art by virtue of their inclusion within this section.
Oilfield operations, such as surveying, drilling, wireline testing, completions, production, planning and oilfield analysis, are typically performed to locate and gather valuable downhole fluids. Various aspects of the oilfield and its related operations are shown in FIGS. 1A-1D. As shown in FIG. 1A, surveys are often performed using acquisition methodologies, such as seismic scanners or surveyors, to generate maps of underground formations. These formations are often analyzed to determine the presence of subterranean assets, such as valuable fluids or minerals. This information is used to assess the underground formations and locate the formations containing the desired subterranean assets. This information may also be used to determine whether the formations have characteristics suitable for storing fluids. Data collected from the acquisition methodologies may be evaluated and analyzed to determine whether such valuable assets are present, and if they are reasonably accessible.
As shown in FIGS. 1B-1D, one or more wellsites may be positioned along the underground formations to gather valuable fluids from the subterranean reservoirs. The wellsites are provided with tools capable of locating and removing hydrocarbons, such as oil or gas, from the subterranean reservoirs. As shown in FIG. 1B, drilling tools are typically deployed from the oil and gas rigs and advanced into the earth along a path to locate reservoirs containing the valuable downhole assets. Fluid, such as drilling mud or other drilling fluids, is pumped down the wellbore through the drilling tool and out the drilling bit. The drilling fluid flows through the annulus between the drilling tool and the wellbore and out the surface, carrying away earth loosened during drilling. The drilling fluids return the earth to the surface and seal the wall of the wellbore to prevent fluid in the surrounding earth from entering the wellbore and causing a ‘blow out.’
During the drilling operation, the drilling tool may perform downhole measurements to investigate downhole conditions. The drilling tool may be used to take core samples of the subsurface formations. In some cases, as shown in FIG. 1C, the drilling tool is removed and a wireline tool is deployed into the wellbore to perform additional downhole testing, such as logging or sampling. Steel casing may be run into the well to a desired depth and cemented into place along the wellbore wall. Drilling may be continued until the desired total depth is reached.
After the drilling operation is complete, the well may then be prepared for production. As shown in FIG. 1D, wellbore completions equipment is deployed into the wellbore to complete the well in preparation for the production of fluid through the wellbore. Fluid is then allowed to flow from downhole reservoirs into the wellbore and then the surface. Production facilities are positioned at surface locations to collect the hydrocarbons from the wellsite(s). Fluid drawn from the subterranean reservoir(s) passes to the production facilities via transport mechanisms, such as tubing. Various types of equipment may be positioned about the oilfield to monitor oilfield parameters, to manipulate the oilfield operations, and/or to separate and direct fluids from the wells. Surface equipment and completion equipment may also be used to inject fluids into reservoirs, either for storage or at strategic points to enhance production of the reservoir.
During the oilfield operations, data is typically collected for analysis and/or monitoring of the oilfield operations. Such data may include, for example, subterranean formation, equipment, historical and/or other data. Data concerning the subterranean formation is collected using a variety of sources. Such formation data may be static or dynamic. Static data may relate to, for example, formation structure and geological stratigraphy that define geological structures of the subterranean formation. Dynamic data may relate to, for example, well production data. Such static and/or dynamic data may be collected to learn more about the formations and the valuable assets contained therein.
Sources used to collect static data may be seismic tools, such as a seismic truck that sends compression waves into the earth as shown in FIG. 1A. Signals from these waves are processed and interpreted to characterize changes in the anisotropic and/or elastic properties, such as velocity and density, of the geological formation at various depths. This information may be used to generate basic structural maps of the subterranean formation. Other static measurements may be gathered using downhole measurements, such as core sampling and well logging techniques. Core samples are used to take physical specimens of the formation at various depths as shown in FIG. 1B. Well logging involves deployment of a downhole tool into the wellbore to collect various downhole measurements, such as density, resistivity, etc., at various depths. Such well logging may be performed using, for example, the drilling tool of FIG. 1B and/or the wireline tool of FIG. 1C. Once the well is formed and completed, fluid flows to the surface using production tubing and other completion equipment as shown in FIG. 1D. As fluid passes to the surface, various dynamic measurements, such as fluid flow rates, pressure and composition may be monitored. These parameters may be used to determine various characteristics of the subterranean formation.
Sensors may be positioned about the oilfield to collect data relating to various oilfield operations. For example, sensors in the drilling equipment may monitor drilling conditions, sensors in the wellbore may monitor fluid composition, sensors located along the flow path may monitor flow rates and sensors at the processing facility may monitor fluids collected. Other sensors may be provided to monitor downhole, surface, equipment or other conditions. Such conditions may relate to the type of equipment at the wellsite, the operating setup, formation parameters or other variables of the oilfield. The monitored data is often used to make decisions at various locations of the oilfield at various times. Data collected by these sensors may be further analyzed and processed. Data may be collected and used for current or future operations. When used for future operations at the same or other locations, such data may sometimes be referred to as historical data. The data may be used to predict downhole conditions, and make decisions concerning oilfield operations. Such decisions may involve well planning, well targeting, well completions, operating levels, production rates and other operations and/or operating parameters. Often this information is used to determine when to drill new wells, re-complete existing wells or alter wellbore production. Oilfield conditions, such as geological, geophysical, and reservoir engineering characteristics, may have an impact on oilfield operations, such as risk analysis, economic valuation, and mechanical considerations for the production of subsurface reservoirs. Data from one or more wellbores may be analyzed to plan or predict various outcomes at a given wellbore. In some cases, the data from neighboring wellbores, or wellbores with similar conditions or equipment, may be used to predict how a well will perform. There are usually a large number of variables and large quantities of data to consider in analyzing oilfield operations. It is, therefore, often useful to model the behavior of the oilfield operation to determine a desired course of action. During the ongoing operations, the operating parameters may need adjustment as oilfield conditions change and new information is received.
In modeling a reservoir, seismic measurements and measurements at the well bore level, both static and dynamic, may be taken. It should be noted that while such measurements may be useful in modeling a reservoir, they may not be sufficient to fully characterize the subsurface reservoir. Additionally, less data about the reservoir may be available at points in the reservoir that are further away from the wellbores. Therefore, certain assumptions may be made about these areas, thereby creating certain degrees of variability in modeling the reservoir.
As such, various techniques, more fully described below, have been developed to take into account these assumptions and create multiple realizations of the reservoir. To this end, the realizations may be constructed such that each realization may have approximately the same probability of occurring. Furthermore, each realization may be a product of the different combinations of measurement data and assumptions used to model the reservoir.
Techniques have been developed to model various portions of oilfield operations such as geological formations, downhole reservoir, wellbores, and surface facilities. Examples of these techniques are shown in Patent/Application Nos. U.S. Pat. No. 5,992,519, WO2004049216, WO1999/064896, U.S. Pat. No. 6,313,837, US2003/0216897, U.S. Pat. No. 7,248,259, US2005/0149307 and US2006/0197759. Existing modeling techniques have typically been used to analyze only specific portions of oilfield operations. More recently, attempts have been made to use more than one model in analyzing certain oilfield operations. See, for example, Patent/Application Nos. U.S. Pat. No. 6,980,940, WO04049216, US2004/0220846 and US2007/0112547. Additionally, techniques for modeling certain aspects of an oilfield have been developed, such as OPENWORKS™ with, e.g., SEISWORKS™, STRATWORKS™, GEOPROBE™ or ARIES™ by LANDMARK™ (see www.Igc.com); VOXELGEO™, GEOLOG™ and STRATIMAGIC™ by PARADIGM™ (see www.paradigmgeo.com); JEWELSUITE™ by JOA™ (see www.jewelsuite.com); RMS™ products by ROXAR™ (see www.roxar.com), and PETREL™ by SCHLUMBERGER™ (see www.slb.com/content/services/software/index.asp).
Typically, for an entire production scenario, multiple realizations of a reservoir model may be created to take into account the various assumptions made about the reservoir as describe above. Furthermore, multiple surface models modeling the surface facilities used to extract or otherwise manipulate the fluids in the reservoir may also be created. The reservoir models and the surface models may then be coupled to form a coupled model, and a simulation may then be executed on the coupled model. However, current techniques require that each model must be manually coupled with one another and manually sent to a remote computing center to be simulated. In the context of hundreds, and even thousands, of coupled models, manually performing these tasks can be very time-intensive and burdensome.